Increase in extreme wet, dry spells in India: Study

The data, collected from the IMD, shows that when rainfall occurs, it is much heavier.

Researchers have said that such conditions increase the risk of floods and droughts. (Reuters)

Even as the India Meteorological Department (IMD) has predicted that the monsoon will be “below normal” this year, researchers at Stanford University, California, have concluded that monsoon in India is becoming more extreme, with significant increase in both wet and dry spells. They have said that such conditions increase the risk of floods and droughts.

“The South Asian summer monsoon directly affects the lives of one-sixth of the world’s population. There is substantial variability within the monsoon season, including fluctuations between periods of heavy rainfall and low rainfall. These fluctuations can cause extreme dry and wet conditions that adversely impact agricultural yields, water resources, infrastructure and human systems,” says the paper, which has been published in the journal, Nature Climate Change.

“The findings are crucial as continuing trends in wet spells can imply increased flooding risk in parts of the region. As we have seen recently in many parts of India, this can lead to loss of lives, spread of diseases and destruction of property… Further, increase in dry spells can also have substantial impact on crop yields, as has been noted in many places including Maharashtra and Andhra Pradesh,” said Deepti Singh, lead author of the paper, from the Department of Environmental Earth System Science, Stanford University, in an interview with The Indian Express.

She said that based on discussions with researchers at the International Water Management Institute (IWMI), the duration and frequency of dry spells can be extremely important early in the agricultural cycle (July-August).

The paper uses statistical methods to analyse changes in several rainfall characteristics between two 30-year periods — 1951-1980 and 1981-2011. The data, collected from the IMD, shows that when rainfall occurs, it is much heavier. Moreover, there are several more periods of below-normal rainfall during the peak-monsoon months, although they may not be as severe.

These results suggest that combined with increasing exposure and vulnerability associated with rapid population growth, land-use change and groundwater depletion, these changing climatic extremes are likely to pose a greater disaster risk to the region. “The observed changes are relevant for managing climate related risks, with particular relevance for water resources, agriculture, disaster preparedness and infrastructure planning,” the paper concludes.

“These results suggest that we are already seeing significant changes similar to what are expected in response to increased greenhouse gas warming. They support anecdotal evidence of climate change by farmers. Some local governments have already had to deal with the consequences of these changes, including the increasing incidences of farmer suicides,” said Singh.